Low level radioactive contaminated hazardous solid waste materials and debris are generated during industrial maintenance, spill response, and building decontamination projects. Such debris can include piping, pumps, valves, duct work, process tanks, wooden and concrete flooring, spill control booms, personnel protective equipment (PPE), soils and a wide variety of other solid items. Disposal of such radioactive contaminated hazardous waste materials is a major concern in the U.S. Low level radioactive contaminated wastes are defined in the Low level Radioactive Waste Policy Act of 1985, as later amended (including Class A, B and C wastes) 40 USC 2021, and also in 10 CFR 61.2. Low level radioactive wastes are generally defined as radioactive waste not classified as high-level radioactive waste (those being transuranic waste, spent nuclear fuel, or byproduct material as defined in section 11e.(2) of the Atomic Energy Act). Low level radioactive wastes characterization does not depend on the level of radioactivity it contains. Solid wastes are defined in Resource Conservation and Recovery Act (RCRA). Hazardous wastes are solid wastes meeting certain criteria as established in (and regulated by) RCRA. See for instance, 40 CFR Part 261. Mixed Wastes are a specific class of hazardous wastes, and include a mix of low level radioactive wastes and hazardous wastes, and are regulated by both RCRA and the Atomic Energy Act (AEA). These types of contaminated materials are generally disposed in landfills, but the contaminated solid materials have to be properly treated and “packaged” for disposal to reduce the potential for spread of contamination by leachate. While the materials of concern are solid materials (as opposed to liquid), some entrained liquids may be present in the materials. In the following, the materials are understood to be such solid low level radioactive contaminated hazardous wastes or “mixed wastes” (as classified by DOE and NRC).
Generally, the contaminated materials are stored on site in temporary containers, such as metal drums or boxes. For transport and disposal, the materials are moved out of the temporary storage containers to an approved disposal container and the approved disposal container is then buried in a landfill. An approved disposal container is generally a highly corrosion resistant container, such as a stainless steel container or a plastic drum or box. Prior to burying of the approved disposal container, the container will be sealed shut, such as by welding the container top shut to prevent fluids from entering or exiting the container. Standard metal boxes or standard metal drums cannot be used for ultimate disposal, unless the hazardous materials in the interior of the metal box are encased in an encapsulating material within the metal container, such as Portland cement. However, encasement of the materials makes that container heavy, and presents problems in shipping due to the weight.
As mentioned, low level radioactive hazardous waste materials may be disposed of using a macro-encapsulation technique. Macroencapsulation is defined as encapsulation of the hazardous materials with (1) surface coating materials or (2) use of a jacket of inert inorganic materials to substantially reduce surface exposure to potential leaching media. See 40 CFR 268.42 One method and device for macroencapsulation of hazardous wastes is described in U.S. Pat. No. 7,074,174, hereby incorporated by reference. As described in that reference, a soft-sided roll off container liner is used. The liner is placed in a standard roll off container, and a layer of treat reagent is placed on the bottom of the liner to absorb fluids that may be present in the wastes. The hazardous wastes are then loaded into the liner interior, and finally free flowing reagents are added (such as Portland cement, or organic activated charcoal) around the hazardous wastes. The softsided liner has three layers of materials, and innermost and outermost layers are closable with a zipper. Once the loaded liner is sealed closed, the roll off container is transported to the disposal side, and the liner/hazardous materials are then slid out of the roll off container for burial. As described, the line's inner layer is a pad or mat or membrane formed from a polyolefin or polyester (such as polytetrafluorethylene), the middle layer is a high density film, (such as a polyethylene, polypropylene or other liquid impervious and chemically resistant synthetic material), and the outer layer is a tear and puncture resistant fabric such as woven polypropylene or polyethylene. However, the requirement of a macroencapsulation layer of Portland cement also makes transportation of such a loaded bag problematic.
Another prior art device and disposal method for disposal of low level radioactive hazardous waste contaminated materials is using a softsided container used as a macroencapsulation device, available from PacTec as HMPPS product, shown in FIGS. 1A and 1B. The HMPPS bag is constructed using a three layer design, having an innermost layer of 12 oz non-woven polypropylene, a middle layer of 12 mil reinforced polyethylene layer, and an outer lay of preferably, 12 oz non-woven polypropylene. The outer layer may include water resistant exterior coating, such as a 3 ml polyethylene coating. Each of the three layers is in essence a separate softsided bag, each with separate closable openings. Each bag has a sidewall, a top portion, a bottom portion a top edge (where the sidewall meets the top portion), and the bags have openings only on the top portion. In a center zip embodiment, the top of portion of the bag can extend substantially above the top edge of the bag.
The final assembled product results in a nested series of bags or layers. These three “bags’ may be joined together, such as sewn together or heat welded together or adhesively bonded, but this is not preferred. The innermost and outermost layers are closeable with a zipper, while the middle layer is closeable with a “ziplock” type of zipper closure device. Each layer can be opened and closed independently from the other layers. The preferred construction is to have the zippers (including ziploc type of toothless zipper closures) traverse down the center of the top portion of each bag, much like the closable opening shown in the U.S. Pat. No. 8,894,282, (incorporated by reference). Cardboard inserts may be provided to line the interior sidewalls to allow the assembled product to be self-standing.
To use the HMPPS softsided container, the three layer container is positioned in a metal shipping container (possibly by placing one bag in the container at a time) or using the cardboard inserts, set up as a self-standing container. All of the layers are opened and the hazardous materials loaded into the container. Preferably a layer of absorbent material (such as sand, kitty litter, plastic or foam pellets, etc.) is placed on the bottom of the innermost layer. LLHZ debris is then loaded into the interior of the disposal bag. Once filled, the remaining void space in the resulting loaded container preferably should be less that 10%, or as required by the disposal site operator. The layers are then closed. The loaded container (or container within a shipping container) is placed on a shipping vehicle for transport to the disposal site. At the disposal site, the bag may be moved using a lifting harness or sling coupled to the exterior of the bag, with a lifting frame or crane (as disclosed in U.S. Pat. No. 8,894,282) or the loaded bag may be slid out of the container for disposal (not preferred) for burial at the site.
The two bags described above are not used for disposal of heavy debris (such as more than 80 lbs per item), or debris having sharp or jagged edges, as the integrity of the bag with such heavy or sharp edged debris could be jeopardized. For disposal of these types of materials, the standard macroencapsulation techniques are used. These include placing the wastes in a stainless steel box or plastic drum, or encased in Portland cement in a standard metal box. An alternative method or bag is needed to address disposal of low level radioactive contaminated heavy debris and debris with sharp edges.